Applications have also been filed directed to an Economical Lifting Devicexe2x80x94Trunk Jack, and Economical Lifting Devicexe2x80x94Jack stand, as described in the present specification.
The invention relates to a low cost consumer device for lifting and supporting an object i.e. a corner of an automobile; particularly to a low cost consumer jack, and also to a low cost two part jacking system including a power unit that can be used to place and elevate a jack stand. The inventor of the present invention is a pioneer of the two part jacking system holding numerous issued and pending patents for a two part jacking system and related products and processes as described below. All such prior art patents and applications are incorporated herein by reference.
Briefly, the commercial two part jacking system consists of a power unit and a set of separate mechanical jack stands. Examples of the two part jacking system and mobile power unit are described in detail in Re. U.S. Pat. Nos. 32,715 and 4,589,630. Some examples of the jack stands are described in detail in U.S. Pat. Nos. 4,553,772; 4,490,264; 5,110,089; 5,183,235 and 5,379,974. The stands are capable of being vertically extended and retracted from the garage floor or road surface and, when extended, can be locked in place at any desired position by a ratchet and pawl assembly. The commercial power unit has a mobile chassis adapted to carry a plurality of the jack stands, and has a pair of lift arms adapted to mate with the outermost jack stand for placement and removal.
In use, the commercial mobile power unit is operated entirely from its handle. It is maneuvered under a vehicle to place a jack stand in a desired location for lift and supporting the vehicle. The power unit is activated from the handle, and this jack stand is then vertically extended to the desired height, thus lift the vehicle on the stand. By operating the controls at the end of the handle, the operator can cause the power unit to disengage from the stand, and the stand will remain locked in its extended supporting position under the vehicle. After the stand is raised and locked in place to support the vehicle or other load in a lifted position, the power unit lift arms are lowered and the power unit is disengaged from the stand and pulled away, leaving the stand in position supporting the load. Another jack stand, carried within the chassis, is automatically transferred to the forward end the chassis for placement at another desired location of the vehicle or for use to lift and support another vehicle.
To lower the vehicle and remove the stand, the power unit is maneuvered to reengage with the stand. The engagement causes any existing jack stands carried within the chassis to be automatically transferred rearward within the chassis. By manually operating a control at the end of the handle, the operator can cause the power unit to reengage with the stand, and to disengage the ratchet locking mechanism of the stand and lower the stand to its original position. The power unit remains engaged with the stand and can be pulled away from the vehicle with the stand carried within the chassis.
The original commercial power units were adapted to carry up to four jack stands within the chassis. Additional jack stands could be purchased and arranged at various stations on the garage floor to reload the power unit, so that a single power unit could be utilized to efficiently place and actuate numerous jack stands. It was found that many commercial users would utilize all of their available jack stands, and the power unit was thereafter useless until another jack stand was available to be extracted and reused. The present inventor developed a slide forward bridge that adapted the power unit to function as a load-lifting jack to more fully utilize the power unit. Co-pending patent applications have been filed on the features of the power unit convertible into a load-lifting device.
Most of the prior art lifting devices, including those of the present inventor, are very rugged xe2x80x9ccommercial qualityxe2x80x9d products involving many castings and machined parts that require welding for fabrication and assembly. It would be highly desirable to design and develop the innovative jack systems in a low cost xe2x80x9cconsumer qualityxe2x80x9d configuration that involved minimal welding and machining during fabrication and assembly.
In view of the foregoing problems and desirable features of a two part lift and supporting system, it is an object of the present invention to provide a consumer jack and a consumer power unit for use with a consumer jack stand, that can be economically fabricated from sheet metal and steel plate with little or no machining, and can be assembled with little or no welding.
The foregoing objects are accomplished by an economical power unit for use with a jack stand, including a base having a rectangular bottom with a forward end for receiving the jack stand and a rearward end having a rear flange extending upward from the bottom with a central aperture therein for receiving a screw threaded actuator shaft. The base has left and right side flanges extending upward from the bottom with each side flange having an aperture near the forward end thereof, and having an increased thickness along the upper portion thereof providing a longitudinal recess formed along the lower portion on the inner surfaces of the flange.
The actuator shaft has a distal end, and has a proximal end extending through the aperture of the rear flange and is rotatably retained within the aperture, and is further adapted to be engaged by an external handle, to facilitate rotation of the shaft. The actuator shaft operates a sliding block having a rectangular bottom and left and right sides that are slideably retained within the longitudinal recesses of the side flanges of the base. The block has a forward end and a rearward end each having a central threaded aperture therein for receiving the forward end of the threaded actuator shaft.
The device includes a pair of lift arms acting in parallel each having a forward end and a rearward end, and has the rearward end pivotally attached to the respective side of the block. A pair of connecting arms acting in parallel each has a forward end pivotally attached at the aperture near the forward end of the respective side flange of the base, and has a rearward end pivotally attached at a pivot point on the lift arms. The forward end of each lift arm has a leveling pad adapted to provide a separated lifting pad for the device.
The power unit is also convertible by a lift bridge, that is adapted to be positioned on the forward ends of the lift arms, whereby the power unit is operable as a load-lifting jack. The bridge is further adapted to be displaced from the forward ends of the lift arms, whereby the power unit is operable for use with the jack stand.
The lift arms each include a track having a recessed channel extending from the forward end thereof to a position away from the forward end thereof for slideably retaining the bridge. A follower member is slideably retained within the channel, with the follower member having a guide pin extending upward from the channel; and the bridge includes a recess in the under surface thereof for engaging the guide pin. The channel of said lift arm further includes a compression spring for biasing the follower member toward the forward end of the channel, and thereby biasing the bridge toward a slide forward position on the lift arm.
The major components of the lifting device can be suitably formed from standard sheet metal and metal plate stock with minimal machining and welding required to form or assemble the components. The base is formed from a piece of sheet metal having a flat pattern defining the rectangular bottom and the respective rear flange, side flanges, and additional flanges, all extending outward from the rectangular bottom. The entire base can be formed from a single piece of sheet metal that is stamped to form the apertures and the periphery defined by the flat pattern; the flat pattern is progressively folded into the base without the need for welding. The block and lifting pad are similarly formed from flat patterns that are readily stamped and folded into the desired configurations without the need for machining and welding.